基于连续小波变换的二维边界层分离点判定

边界层分离点位置的检测是实现主动流动控制的基础和关键,采用可挠性的微型热膜传感器阵列对二维边界层分离点进行实时在线测量是一种新方法。针对小波变换在边界层分离流多尺度旋涡处理方面的优势,采用Morlet连续小波变换对传感器阵列信号进行时频域分析,根据边界层分离前后脉动旋涡频率段在时域上的百分比来确定分离点位置。结果显示采用该方法可以有效地判定出边界层分离点振荡区间。

A Criterion for 2-D Boundary Layer Separation Point Based on Continuous Wavelet Transform

Detection of the location of the separation point of a boundary layer is important in active flow control field.Flexible micro-thermal-film sensor array based on MEMS was used to detect boundary layer separation point.The test was carried out in a NACA0012 aerofoil in a wind tunnel. Due to the advantage of wavelet transform for processing unsteady signal of boundary layer separation flow,Morlet continuous wavelet transform was adopted to process sensor array signal and analyze the signal in time-frequency domain.When the boundary layer separates from the aerofoil wall surface,the typical middle frequency segment of fluctuating vortexes occupancy percentage will decrease greatly,and the percentage is used to determine the flow boundary layer separation point scope.The result shows that continuous wavelet transform criterion can determine the boundary layer separation point scope effectually.